[LUNI] WANTED: Email Server Holy Grail

[bgallia at k9.mw.luc.edu]

  Your looking at projects authored by people that think small.  Also, NFS
is *NOT* the way to achieve scale-ablity.  File locking across NFS tends
to kill any benfits of being able to build a server farm.

  From the same school that brought such scalable kick ass services such
as the Andrews File System[1] is... [drum roll]... Cyrus IMAP[2]!  These
guys thought of everything.  It uses maildir format by default.  You can
read/write from server-side folders.  It uses LMTP (Local Mail Transport
Protocol) so that your SMTP MTA's can be one different machines than your
IMAP servers.  The IMAP daemon supports proxy mode so that the physical
location in which user's mail is stored can be moved from server to server
but the user still connects to the same IMAP proxy for seamless
connections to the new location.  Intermix this with reiserfs and PostFix
and you have an unstopable streamlined combination that just kicks ass to
the point of making it look like UW is implimenting things in Logo (turtle
go up, turtle go down, turtle go forward 10).  :)

  If you are really gun-ho on a centralized storage method then go with a
SAN like method like GFS[3], **NOT** Nightmare File System.

  If you need more specifics on how to do scale-able email systems,
contact the Moongroup[4].  At the very least, read through some of the
free E-Mail documentation links[5] including the Exchange Server
Replacement HOWTO[6].  But you may find that providing them with your
specifications and goals that a couple hours of offsite consulting[7]
from them may save you money in the long run from going down the wrong
path.

References:
[1] http://www.openafs.org/
[2] http://asg.web.cmu.edu/cyrus/
[3] http://www.sistina.com/products_gfs.htm
[4] http://www.moongroup.com/
[5] http://www.moongroup.com/pages.php?page=docs
[6] http://www.moongroup.com/docs/exchange-replacement-howto/
[7] http://www.moongroup.com/products.php


On Fri, 2 Nov 2001, Herbie Herbert wrote:

> Yes, we've all heard it, this email system is 100% NFS safe, blah, blah, blah.
>
> I'm trying to get a system, that will eventually scale to 50 - 100,000 users. The premise is one
> big NFS box to hold the mail and lots of little linux boxes to take delivery of it, and to allow
> users to access it.
>
> We thought that Maildirs were the way to go NFS safe and all, but the big snag is there is no
> useable IMAP server for it. Our email client of choice (not mine, someone who went before me) is
> Eudora which has a very poor performance IMAP wise and puts a lot of load on the server, and
> unfortunately asking the users to change to something suitable is not an option I have.
>
> So we tried Courier, no good, one Eudora session can thrash it, how will it cope with thousands?
> We tried UW IMAP patched for Maildir, had a nice performance but several other limitations, like
> mail cannot be moved to the server, only read from it via IMAP, which is an issue for people who
> keep their sent-mail folder on the server.
>
> So now we're back at Square One, either looking for an IMAP server that will support Maildir under
> harsh conditions. Or a mailbox format the is NFS safe, and already supported by UW IMAP. Or is
> this something as likely as Bernstein and Crispin becoming lovers?
>
> Any ideas, anyone?
>
> herbie
>
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